The Coil Gun has a modular design. Each 3D printed module houses of a capacitor bank, an accelerator coil, an optical trigger and a charging circuit. The modules can be stacked. The modules could probably be improved by adding circuitry for sensing the speed of the incoming projectile, and then use this as a factor when calculating the timing of the next pulse.

You can find more info on the charging circuit and modules on GitHub, but I will not provide a full schematic for this device. It looks (and probably also performs) like a toy, but the energy levels involved are lethal. Each module will dump approximately 670A into the drive coil in 8ms. If you accidentally touch a HV terminal, you won’t just get burnt – blood vessels in your body will most likely explode. A “capacitor mishap” will guarantee a visit to the emergency room – dead or alive.